USPTO Patents Application 10004917

PATENT SPECIFICATION c

DRAWINGS ATTACHED

996.841

Date of Application and filing Complete Specification Sept, 18, 1963.
No. 36795163.

Application made in Germany (No. D399A6 X///47f) on Sept. 29, 1962.

Complete Specification Published June 30, 1965.
© Crown Copyright 1965.

Index at acceptance: — Fl P(4, 10X, 18 A); F2 VB
Int CL :— F 03 c

COMPLETE SPECIFICATION

Improvements relating to means for Damping Pressure
Shocks in Hydraulic Systems

10

15

20

25

30

35

40

We, Daimler-Benz Akttengeseixschaft,
of Stuttgart-Unterturkhekn, Germany, a
Company organised under -the laws of
Germany, do (hereby declare the invention,
for which we pray that a patent may be
granted to us, and the method by which it
is to be performed, to be particularly des-
cribed in and by the following statement: —

This invention concerns improvements
relating to means for damping pressure shocks
in ducts of hydraulic systems installed in
motor vehicles, comprising a pipe or other
duct communicating between the delivery of
a pump, especially a piston pump, and a
pressure accumulator to which hydraulic
operating and/or control devices are con-
nected.

Piston pumps for delivering a pressure
medium to hydraulic devices 'produce pressure
shocks which are -propagated in the medium
and in the pipes and which, for example
when a -pipe is located against a wall off a
vehicle body, may produce troublesome noise
in the latter.

Interference devices have already been pro-
posed for damning vibrations produced by
intermittent delivery of the medium. How-
ever, the provision of dead spaces in the
pipes effects damping of predetermined
natural frequencies only. In addition, such
damping results in loss of energy and in-
creased expense for the provision of the
damping devices. Finally, because of lack of
space, such devices cannot always be accom-
modated an a motor vehicle.

The pressure accumulator themselves have
also been used for damping pressure shocks,
in which case ihe pipe between the accumu-
lator and the oump had to be kept as short
as possible and could not be disposed against
a wall of a vehicle body. As, however, the
lines leading to the operating devices had
to be connected directly to the end of

[Price 4j. 6d.]

the pipe which adjoins the accumulator and,
because of their length, these hues had to
be secured to a wall, the .pressure shocks
were transmitted to the said lines and still
gave rise to considerable noise. It is am
object of the present invention to provide
means by which the shocks are damped and
noise produced by die shocks is reduced or
eliminated.

According to the invention, a hydraulic
system in a motor vehicle includes a first
duct communicating between the delivery
of a pump and a pressure accumulator, a
second duct communicating between the said
accumulator and hydraulic operating and/or
control devices, and means for damping /pres-
sure shocks comprising an ante-chamber
which forms a passage extending straight
through between the said first duct and
the opening to the accumulator and having
a cross-section larger than those, of the first
and second ducts. Such an arrangement is
applicable with especial advantage in the case
of a system, installed on a motor vehicle,
in which the pump is a piston pump.

Preferably, the cross-section of the mouth
of the first duct opening into the ante-
chamber is larger than that of the mouth
of the second duct opening into the ante-
chamber. Depending upon die differences in
cross-section, pressure shocks produced by a
piston pump can he reduced to a desired
extent.

The ante-chamber may be provided in an
intermediate union piece attached directly to
the accumulator and having a- number of
branches corresponding to die number of
connections to be made to the said piece.
The cross-section of the branch communicat-
ing with the accumulator may be equal to
that of the mouth of the first duct opening
into the ante-chamber. The cross-section of
the said branch may be equal to that of the

45

50

55

60

65

70

75

80

85

2

996,841

ante cham ber, which permits of a simple in-
expensive union -piece

Due to the ante-chamber between the
end of the first duct and the accumulator on
5 the one hand and die second duct on the
other hand, and also due to the different
cross-sections dn the union piece, smoothing
of the shocks or vibrations in the pressure
medium is achieved, so that the said medium

10 flows into the second duct without serious
shocks and produces little or no noise at
the walls of the vehicle body.

Embodiments of the invention by way of
example are illustrated dn the accompanying

15 drawing, in .which:

Figure 1 shows one form of damping means
in? conjunction- with a pump and pressure
accumulator for a system on a motor ve hi cle,
partly in section, and

20 . Figure 2 similarly shows another form of
damping means.

In Figure 1, 10 designates a piston pump
and 11 a pressure accumulator. A pipe 12
connects the pump 10 through an inter-

25 mediate union' piece 13 to the accumulator

11. In addition to a tench 13 l for the pipe

12, which is relatively short and is not
attached to a wall of the vehicle body, and
a branch 13 u screwed into the body of

30 the accumulator 11, die union piece 13 has
a branch 13 m connected to a tripe which
leads to hydraulic operating and/or control
devices and which can be attached to walls
of the body. The bores of the branches 13 1

35 to 13 m open into an ante-chamber 14 which
immediately precedes the accumulator 11 and
whose internal diameter D a is larger than?
the internal diameter D 2 of the branch 13 1 ,
which is, as far as possible, the same as that

40 of the pipe 12. The said diameter D* is
larger than the internal diameter D L of the
. branch 13 n 5 which may be the same as the
diameter of the pipe leading to die operating
and/or control devices. The diameter of die

45 branch 13 u is equal to the diameter D 4 . To
avoid losses due to tfrrotding effects, the pipe
leading to the said devices may have a
diameter larger than the diameter Dj of
die branch 13 m .

50 The arrangement illustrated in Figure 2,
comprising a union piece 23 with branches
23\ 23 u and 23 m and antechamber 24,
differs solely , in that the diameter of die
branch 23 u connected to the accumulator II

is equal tr> the diameter U 3 of the chamber 55
24.

Due to the different diameters D l3 D., D 3
of the said branches and antechamber, 14
or 24, pressure shocks can be damped "to
an extent dependent upon the magnitudes 60
of the difference in diameter. Even when
relatively 'long pipes leading .to operating
and/or control devices bear against walls
of the vehicle body, Jitde or no noise is
tr ansm itted ther eto. 65
WHAT WE CLAIM IS:—
1. An hydraulic system in a motor vehicle,
including a first duct communicating between
the delivery of a pump and a pressure accu-
mulator, a second duct communicating 70
between the said accumulator and hydraulic
operating and/or control devices, and means
for damping pressure shocks conrprising an
ante-chamber which forms a passage extend-
ing straight through between the said first 75
duct and the opening to the accumulator and
having a cross^section larger than those of.
the first and second ducts.
. 2. A system according to claim 1, wherein.'
the cross-section of the mouth of the first 80
duct opening into the ante-chamber is larger
than that of the mouth of the second duct
opening into the ante-chamber.

3. A system according to claim 1 or

2, wherein the ante-chamber is provided in 85
an intermediate union piece attached directly
to the accumulator and having a number
of branches corresponding to the number of
connections to be made to die said piece.

4. A system according to claim 3, wherein; 90
the cross-section of the branch communicating
with the accumulator is equal to that of

the mouth of the first duct opening into
the ante-chamber.

5. A system according to claim 3, wherein 95
the cross-section of the branch corxununicating
with the accumulator is equal to that of die
ante-chamber.

6. An hydraulic system with means for
damping pressure shocks substantially as 100
hereinbefore described with reference to
Fagure 1 or Figure 2 of the accompanying

JENSEN & SON,
Agents for the Applicants,
77, Chancery line,
London, W.C.2,
Chartered Patent Agents.

Leamington Spa: Mated for Her Majesty's Stationery Office by the Courier Press.— 1965.
Published at The Patent Office, 25, Southampton Buildings, London, W.C.2, from which copies may be obtained.

996841 COMPLETE SPECIFICATION

1 SHEET nis Rawing Is a reproduction of
the Or\glno\ on a reduced scale

Fig.2

23*23"